Combined exhaust silencer and heat exchanger



Get. 8, 1968 P. A. CUSHMAN COMBINED EXHAUST SILENCER AND HEAT EXCHANGERFiled July 12, 1966 EXHAUST FLOW I? 64 K n 30 2e o l-sea IZ i 0 L 20 0 O,4\ &-|0 22\ o\22 28 l 38 o] 3oN d m 64 eo 56 g I6 68 Fig.3

INVENTOR.

PAUL A. CUSH MAN United States Patent 3,404,731 COMBINED EXHAUSTSILENCER AND HEAT 1 EXCHANGER Paul A. Cushmau, 6791 Alamo Way, SanDiego, Calif. 92115 Filed July 12, 1966, Ser. No. 564,593 4 Claims. (Cl.16551) ABSTRACT OF THE DISCLOSURE This is a combined exhaust mufiier andheat exchanger, for use with an internal combustion engine, ordinarilyon a boat or other vehicle, to suppress noise while providing for a hotwater supply for the boat or other vehicle. The bafiies are flat,transverse, tightly wound, spiral coils of pipe in spaced relationdefining baflie chambers therebetween and the spirals feed intomanifolds both disposed longitudinally in an open channel runningaxially of the casing.

The present invention relates to exhaust gas treatment and specificallyto an exhaust silencer incorporating a heat exchanger. While adaptableto a variety of engines and installations, the unit is particularlyelfective when used on a boat, wherein the exhaust is composed of amixture of engine exhaust gases and water from the engine coolingsystem. In addition to suppressing exhaust noise the unit will provide asupply of hot water, which is heated rapidly to a useful temperature butcannot boil, since the exhaust heat is held below boiling point by thewater in the exhaust.

Conventional heat exchangers utilizing engine exhaust are usually in theform of jackets around exhaust pipes, or have heat collecting elementsimmersed in the gas flow. In the unit disclosed herein the exhaust isconducted through a casing in which coiled water pipes are arranged toform silencing baflles and are connected together in a novel manner formaximum flow efliciency with a'variety of possible hot water systemconnections, the piping assembly being self-supporting and providingsupports for the unit if required.

The unit, its structure and a typical installation are illustrated inthe drawings, in which:

FIGURE 1 is a top plan view of the unit with one half of the casingremoved;

FIGURE 2 is a sectional view taken on line 22 of FIGURE 1, with thecasing complete; and

FIGURE 3 is a diagram of a typical exhaust and hot Water system.

Similar characters of reference indicate similar or identical elementsand portions throughout the specification and throughout the views ofthe drawing.

The unit comprises a casing having a cylindrical expansion chamber 12,with a reduced diameter inlet 14 at one end and a corresponding outlet16 at the other end. Casing 10 is split diametrically along its lengthinto two identical halves 18A and 18B, which have confronting flanges 20along both sides and are secured together by bolts 22, or similar means.Any suitable sealant or gasket may be used between the flanges toprevent leakage.

Along one side of the axis of expansion chamber 12 is a manifold pipe 24having elbow-like end connections 26 and 28 projecting outwardly throughthe casing, the flanges 20 having arched portions 30 to fit closelyaround and secure the end connections. Along the other side of the axisof expansion chamber 12 is a similar manifold pipe 34, having outwardlyprojecting end connections 36 and 38. Spaced longitudinally in theexpansion chamber and surrounding the manifold pipes are heat exchangercoils 40 of small diameter tubing. Each coil is of spiral form in aplane substantially perpendicular to the axis of casing 10, the innerend 42 of each coil being connected to one manifold pipe and the outerend having an extension 44 which passes across a portion of the spiralto the other manifold pipe. As illustrated the outer end extension 44 ofone coil 40 is connected to manifold pipe 24, while the outer end of thenext adjacent coil is connected to the manifold pipe 34. The coils orspirals are alternated in this manner so that flow is reversed fromoutside to inside in every other coil, ensuring more efficientscavenging and transfer of heat. With the ends of both of the manifoldpipes securely held between the halves of the casing and the coils fixedto the manifold pipes, the entire heat exchanger piping assembly is heldin proper alignment Without additional supports. The

end connections of the manifold pipes are indicated as being screwthreaded, but any suitable pipe connecting means may be used.

The spaces between the coils 40 comprise baflle chambers 46 whichprovide the noise suppression action. Although the coils do not formsolid walls there are effective chambers formed which are generallydisc-shaped, extending transversely of the casing, and these chambersallow multiple expansions of the pressure pulses in the exhaust flow andhave been found to provide a con-siderable degree of sound suppression,the basic technique being well known in some types of silencers. Thecoiled pipe may be much more closely spaced than illustrated in thedrawing to provide a more solid wall, each coil being as large aspossible tominimize the space between the outside of the coil and thecasing wall. The complete assembly has an open central passage 48,approximately the same cross sectional area as the exhaust inlet andoutlet to avoid back pressure, with longitudinally spaced, laterallyextending bafile chambers 46. The manifold pipes 24 and 34 extend alongopposite sides of the central passage 48 and cause a minimum ofobstruction to the exhaust flow.

In a typical installation, as shown in FIGURE 3, the unit is installedat a convenient position in the engine exhaust pipe, with an inlet pipe50 inserted in inlet 14 and an outlet pipe 52 in outlet 16. Sleeve typegaskets or O-rings may be used around the exhaust pipe sections toensure good seals when the casing halves are clamped together. Ifsupport is necessary, suitable brackets 54 or the like may be attacheddirectly to two or more of the manifold pipe end connections asindicated in broken line.

The hot water system includes a tank 56 in which hot Water is stored, afaucet 58, or similar outlet being provided for convenient use. From thelower end of tank 56 a supply pipe 60 leads to end connection 26 and areturn pipe 62 leads from end connection 38 back to the top of the tank.By using diagonally opposed end connections a maximum circulation ofwater is obtained. However, any pair of end connections may be useddepending on the installed position of the unit and the flow involved.The unused end connections 28 and 36 are sealed by blank end caps 64.For a high flow rate all four end connections may be used by addingsupply and return pipes 66 and 68, respectively, with appropriateconnections to a common or separate storage tanks or delivery points.

Since the flow characteristics of the unit are substantially symmetricalabout the axis it can be installed with the exhaust entering from eitherend and the hot water circuit made to any convenient connections.

In a boat the mixing of water with the exhaust gases prevents theexhaust temperature from rising above the boiling point of water, so thewater in the hot water system will not boil and cause dangerouspressures to build up. For maximum heat exchange conductivityandcorrosion resistance, the piping is preferably of stainless steel orsimilar material. However, since the exhaust temperature is maintainedat a reasonably low level, the casing 10 can be made of a moreeconomical material, such as glass fiber reinforced plastic, whichserves as an insulator to retain the heat.

By making the casing in two halves the unit is easily dismantled forcleaning and servicing. With one half of the casing removed, as inFIGURE 1, the entire pipe assembly can be lifted out as a unit tofacilitate cleaning of the coils and testing for leaks. The innersurfaces of the casing are then completely unobstructed and any depositsthereon are easily removed.

It is understood that minor variation from the form of the inventiondisclosed herein may be made without departure from the spirit and scopeof the invention, and that the specification and drawing are to beconsidered as merely illustrative rather than limiting.

I claim:

1. A combined exhaust silencer and heat exchanger, comprising:

a substantially cylindrical casing enclosing a chamber and having aninlet and an outlet at opposite ends thereof;

a pair of manifold pipes extending longitudinally of said casing andhaving end connections externally of the casing;

a plurality of spirally coiled pipes spaced longitudinally in saidchamber and substantially normal to the axis of the casing, each of saidcoiled pipes having one end connected to one of said manifold pipes andthe other end to the other manifold pipe;

the central portions of said coiled pipes being open and defining anaxial exhaust conducting passage, both said manifold pipes being in saidpassage;

and said coiled pipes being generally flat spirals defining therebetweengenerally disc-shaped noise suppressing bafile chambers extendingtransversely of the casing, the inner and outer ends of said coiledpipes being alternately connected to the same manifold pipes so thatfiow is from the outside to inside in every second spiral and frominside to outside in the intervening spirals.

2. The structure of claim 1, wherein each of said mani fold pipes hasend connections at both ends thereof for connection to a fluid system,said end connections extending through and being secured in the sides ofsaid casing, whereby the manifold and coiled pipe assembly is entirelysupported by the end connections.

3. The structure of claim 2, wherein said casing is composed of twolongitudinally separated portions, said end connections extendingbetween the portions'andsaid casing having means for clamping theportions together upon said end connections.

4. A combined exhaust silencer and heat exchanger,

comprising:

a substantially cylindrical casing enclosing a "chamber and having aninlet and an outlet at opposite ends thereof;

a pair of manifold pipes secured in said chamber along opposite sides ofthe axis thereof and having end connections externally of the casing;

a plurality of spirally coiled pipes spaced longitudinally in saidchamber and substantially normal to the axis of the casing, each of saidcoiled pipes having one end connected to one of said manifold pipes andthe other end to the other manifold pipe;

the central portions of said coiled pipes being open and defining anaxial exhaust conducting passage;

the spaces between said coiled pipes constituting noise suppressingbaffie chambers;

each of said manifold pipes having end connections at both ends thereoffor connection to a fluid system, said end connections extending throughandbeing secured in the sides of said casing, whereby the manifold andcoiled pipe assembly is entirely supported by the end connections; and

said casing being composed of two longitudinally separated portions,said end connections extending between the portions and said casinghaving means for clamping the portions together upon said endconnections.

References Cited UNITED STATES PATENTS 389,900 9/1888 Pratt et al165-163 676,770 6/1901 Rayner 165-163 X 1,049,014 12/1912 Weir 165-163 X1,391,709 9/1921 Wood et al. 165-52 1,646,786 10/1927 Eatinger 165-411,726,531 9/1929 Andel 165-41 2,143,287 1/1939 Smith 165-163 3,324,5336/1967 Watteau 165-134 X 2,027,886 1/1936 Shull 165-175 X 2,429,66310/1947 Beatty 165-175 X FOREIGN PATENTS 452,821 11/ 1927 Germany.

ROBERT A. OLEARY, Primary Examiner.

A. W. DAVIS, Assistant Examiner.

